The present invention relates to an idler wheel axle, and more specifically to an idle wheel axle assembly for individually mounted wheels.
An idler wheel axle is described in WO 98/24674. This known idler wheel axle is designed in actual fact as a driven axle, a drive being fastened to the outside of the chassis frame on each longitudinal side of the chassis. By virtue of a primary suspension provided between the carrying frame and a chassis frame carrying the drive, the drive is connected to the wheel via a cardanic double coupling. In this case, a first drive-side coupling plane is arranged on the outside of the drive and a second driven-side coupling plane lies directly on the inside of the wheel. The shaft, thereby functioning as a cardan shaft, runs continuously, with a corresponding length, between the two coupling planes of the cardanic double coupling. The advantage of this known idler wheel axle is that the axle and the drive can have a small construction width, in order, for example, to make it possible to have even narrow-gage vehicles, at the same time with a small car body width, without the chassis projecting in a disturbing way. A further advantage is that the mounting of the wheel is arranged within the latter, with the result that a good load-bearing capacity and a long useful life are achieved. This solution has a disadvantage, however, when it is necessary to have a maximum central-aisle width (as is customary, for example, in dropped-frame cars) limited only by the spacing of the wheels and necessary transverse-spring travels and transverse-spring free spaces, since this central-aisle width is restricted by the coupling plane arranged on the inside of the wheel. The fact that access to wheel components, such as, for example, the wheel mounting, for maintenance work is impeded by the coupling plane may likewise be a disadvantage. Moreover, in the case of adaption to further, for example even smaller gages, virtually the entire construction would have to be changed.
DE 44 29 889 A1 describes another chassis, in which the wheels, together with the outside drive, are arranged externally on the frame. Here, too, the wheels are connected to the drive in each case via a cardanic double coupling, but the driven-side coupling plane lies directly on the outside of the wheel and the wheel carrying frame is arranged between the insides of the two wheels of an axle. Adaption to different, in particular smaller gages consequently presents a particular problem.
In the applicant""s previous German patent application DE 199 30 424.6, it was proposed, on the basis of WO 98/24674, that the shaft terminate in a coupling plane formed directly on the outside of the carrying leg. This results in particularly high variability in application, especially with regard to adaption to smaller gages, while at the same time preserving the advantage of an optimum design of the wheel mounting by the latter being arranged within the wheel. Maintenance work is also made easier. To adapt the axle to a different, for example smaller gage (for example, 900 mm), it is necessary merely for the length of the wheel-carrying axle stub of the carrying leg and of the shaft to be adapted to the desired wheel position corresponding to the gage. As regards a driven axle, however, all the drive components can be left unchanged, because the shaft then forms an intermediate drive shaft which is connected to an actual drive shaft in the coupling plane. As a result, a version, such as is known from the abovementioned DE 44 29 889 A1, may be used as a drive unit. All the advantages according to WO 98/24674 are nevertheless maintained. Furthermore, in the case of a nondriven axle, the shaft may be utilized as a braking shaft by being connected to a braking device in the coupling plane.
Moreover, in the proposed idler wheel axle according to DE 199 30 424.6, this provision, in addition to the wheel mounting arranged completely with two part bearings within the orifice of the wheel, for the shaft to be mounted in the orifice of the carrying leg via a further rotary bearing which therefore, as a whole, forms a third part bearing. However, in order to avoid tolerance-related errors of alignment between the three part bearings, this version is highly complicated in manufacturing terms.
The object on which the present invention is based is to provide such an idler wheel axle, by means of which, while the remaining advantages described are preserved, optimized stability, particularly in the region of the wheel mounting, is achieved at a low outlay in manufacturing terms.
This is achieved, according to the invention, in that the wheel mounting consists of (only) two part bearings, and the first part bearing is arranged within the orifice of the wheel radially between the latter and the axle stub of the carrying leg, while the second part bearing is arranged, offset axially and radially to the first, within the orifice of the carrying leg radially between the latter and the shaft.
This advantageous configuration affords the appreciable advantage that the part bearings, of which only two are provided, can be brought into alignment in a substantially simpler way. This is a xe2x80x9cdividedxe2x80x9d wheel mounting, the first part bearing being arranged, as before, within the wheel, that is to say in that region of the wheel orifice which is defined by the axial width or thickness of said wheel. According to the invention, the second part bearing has been displaced axially into the region in which the third part bearing was provided in the proposed idler wheel axle. There is therefore virtually a xe2x80x9cfusionxe2x80x9d of two part bearings. As a result, the wheel, together with the shaft, forms virtually a unit which is mounted in its entirety via the two part bearings arranged so as to be offset axially, while a bearing load-bearing capacity and therefore useful bearing life which are optimum in the existing construction space are achieved.
Further advantageous design features of the invention are contained in the subclaims and the following description.